The invention concerns a prosthetic element (1) with an outer surface defining an interface to the surrounding bone or fibrous tissue, wherein the prosthetic element (1) is provided with at least one internal anchoring cavity (6) for the growing of tissue and a least one guide means (5) for a cutting tool. The guide means (5) and the anchoring cavities (6) are positioned essentially within the perimeter/circumference of the prosthetic element (1) defined by the outer surface of the prosthetic element (1). The anchoring cavities (6) and the guide means (5) are interconnected and at least one of the anchoring cavities (6) and/or the guide means (5) has an opening in the outer surface for the growing of tissue into the element (1).